1. Field of the Invention
The present invention relates to a method and apparatus for providing a lighted mask for underwater divers by utilizing a blue green light for greater depth penetration of underwater illumination in sea water. More particularly it relates to a lighted dive mask using light emitting diodes (LEDs) as a monochromatic light source for providing blue green spectrum illumination.
2. Description of the Prior Art
Lighted dive masks have been utilized in past attempts to provide illumination for underwater divers to read their gauges. An example is U. S. Pat. No. 5,224,772, issued Jul. 6, 1993, to Vincent E. Fustos for an illuminated dive mask. Listed in that patent are other patents relating to lighted dive masks.
The problem with attempting to provide illumination for divers underwater is related in part to the factor of light transcissivity in the medium. Sea water, where most critical underwater diving visibility occurs, absorbs electromagnetic radiation whereby it attenuates light. Research has shown that approximately 60 percent of light is absorbed in the first meter of sea water depth; that 80 percent is absorbed in the first 10 m; and 99 percent is absorbed in the first 150 m. Longer wavelengths (red end) are absorbed preferentialy. Shorter wavelength""s (bluexe2x80x94green) are transmitted deeper (farther). That is why sea water appears blue green at depth: the observer sees what is reflected back to h is or her eyes. Clear water is penetrated deeper by light because there is less reflection absorption by particles in the water. It has been determined that the xe2x80x9coptical windowxe2x80x9d or wavelength of light that penetrates sea water the farthest is 543 nanometers (nm): that specific wavelength of light propagates farthest through sea water.
An underwater light source that is xe2x80x9cwhitexe2x80x9d (producing red, green, and blue wavelength output) wll give the most natural color rendition of the objects viewed. It requires a substantial amount of energy to produce adequate illumination underwater from a xe2x80x9cwhite lightxe2x80x9d source. This level of light cannot be achieved by the illuminated dive mask disclosed in the prior art patent to Fustos and similar devices: the available power sources which can be carried in a dive mask are insufficient to create the energy required for sufficient underwater fight penetration.
Light from a monochromatic light source, such as a light emitting diode (LED), can produce efficient and adequate illumination for a diver in the green region due to the photopic responsiveness of the human eye. The monochromatic light source wavelength range most suitable for underwater illumination purposes is 520-560 nm. Very recently LED""s have been manufactured that produce a typical wavelength output very close to the xe2x80x9coptical windowxe2x80x9d of sea water. Thus, their output will penetrate se a water the farthest. The present invention utilizes these newly developed LEDs of a specific wavelength, both in a continuous on condition and in an intermittent hashing condition, to provide a monochromatic light source for underwater illumination.
Reference is made to U.S. Pat. No. 4,254,451, issued Mar. 3, 1981, to James A. Cochran for a sequentially flashing device for personal ornamentation. While not related to underwater dive masks, light emitting diodes are used in eyeglass frames as decorative apparatus surrounding a persons eyes. Employing sequential flashing LED""s obviously does not teach the use of LED""s of any type for underwater illumination, let alone make obvious the specific wavelengths required for sea water light penetration.
The present invention is a lighted mask for underwater divers. It i s comprised of a frame for supporting a view lens and for positioning the mask on a diver""s face and enclosing the diver""s eyes. An LED light source is mounted on the frame of the mask which is capable of emitting monochromatic light between 425 and 575 nm. Light emitted from the LED is directed to the area in front of the mask whereby light from the source is focused in the direction the mask wearer is looking. A power source is mounted in the mask for the light source and electrically connected thereto. A diver operable switch means is mounted in the mask for electrically connecting the light source to the power source and for controlling the on and off status of the light source.
It is therefore an important object of the present invention to provide a mask for underwater divers which utilizes light emitting diodes for providing underwater illumination.
It is another object of the present invention to provide a lighted mask for underwater divers which provides monochromatic light in the blue green spectrum.
It is a further object of the present invention to provide a lighted mask for underwater divers which provides the greatest amount illumination for the smallest power requirement.
It is still another object of the present invention to provide a lighted mask for underwater divers in which the illumination source is self-contained and can be utilized as a signaling device to other divers.
And it is yet a further object of the present invention to provide a lighted mask for underwater divers in which the illumination source can be actuated to on, intermittent operation, or off by a push button switch formed integral to the mask.
Other objects and advantages of the present invention will become apparent when the apparatus and method of the present invention are considered in conjunction with the accompanying drawings.